济阳坳陷早古生代层序划分与石油地质条件

The Sequence Stratigraphic Division and Petroleum Geologic Condition of Lower Paleozoic in Jiyang Depression

济阳坳陷下古生界整体表现为两大基准面旋回,即寒武系馒头组至奥陶系冶里-亮甲山组和奥陶系下马家沟组至八陡组,两大旋回对应2个超层序8个层序,每个层序均由海侵体系域和高位体系域组成。生储盖配置关系研究表明,超层序A烃源岩总体不发育,而其顶部亮甲山组白云岩是重要的潜山油气藏储集层;超层序B顶部的风化壳发育多期岩溶作用,储集层条件优越,是潜山油气藏的主要储集层,马家沟组沉积期的泥灰岩和厚层灰岩有机质含量较高,是潜在的烃源岩。该区上古生界下部的厚层暗色泥岩是一套优质的区域性盖层,与下伏的寒武系和奥陶系可构成优越的生储盖组合,对形成原生油气藏十分有利。

The Lower Paleozoic in Jiyang depression could be divided into two supper sequences （Sequence A and Sequence B） or two big datum-level cycles which were Cambrian Mantou group to Ordovician Yeli-Liangjiashang group and Ordovician Lower Majiagou group to Badou group. They correspond to eight sequences that are made up of transgressive system tract and high system tract for each one. The assembled relations among source-reservoir-cap rocks show that the source rocks in Sequence A are not developed as a whole, but the dolomite of its Liangjiashan group is an important buried hill reservoir rock. The multi-stage karstifications are found in the weathering crust in top of Sequence B, with superior reservoir condition, and can be as major reservoir rock in the buried hill reservoir. The argillaceous limestone and thick limestone of Majiagou group should be as potential source rocks for the reason of higher content of organic matter. The thick dark mudstone beneath the Upper Paleozoic acts as a preferable regional cap formation, forming a good sourcereservoir-cap rock assemblage along with underlying Cambrian and Ordovician systems. These are the favorable conditions for shaping original oil-gas reservoirs in this area.